Most fun lens in my bag. I shoot full frame Canon 5D Mk II and have to be careful to keep my feet out of the frame.

Cons:

Manual focus/Aperture ring on lens.

I have Canon 5D Mk II and all L lenses. I bought the Sigma 8mm fisheye a few years back for $900 and it was a fine lens but a tad soft for that price. I eventually sold it and recently bought the Rokinon 8mm fisheye for $233. I wasn't expecting much at that price but it is sharp and produces great photos. The Sigma produces round images vs the Rokinon which have the top/bottom cut off. The Rokinon is also manual focus and you must set the aperture with the ring adjustment on the lens (not in camera). I have not found this to be nearly as bothersome as it reads as I have quickly adjusted to it. You want to keep the aperture at f/8 & above for best results - anything below gets a bit softer. Side by side the Sigma is better than the Rokinon but its not nearly the $650 price difference better and I am happy & content with this fun little lens. For those not familiar with fisheye photography, this lens will make you see the world very differently and from a fun & creative perspective. Buy this lens and I guarantee you will shoot with a big smile on your face and then smile again when you download/view them on your computer.